US7862310B2 - Fuel pump - Google Patents

Abstract

The invention relates to a pump module (2) comprising a housing part (4) with precisely determined force introduction points (25) in relation to adjacent components. Supporting elements (24, 27) and a groove (26) are located between the force introduction points (25) and a disc element (20) that comprises a partially annular channel (10). Forces that are introduced into the housing parts (4) thus lead to negligible deformations in the areas of said housing parts (4) that are adjacent to the impeller.

Description

BACKGROUND OF THE INVENTION

The invention relates to a fuel pump with a pump stage driven by an electric motor, with a jacket surrounding the electric motor and the pump stage and having an impeller arranged rotatably between two casing parts of the pump stage, with an inlet duct arranged in one of the casing parts and an outlet duct arranged in the opposite casing part, with rings, arranged in the impeller, of guide blades delimiting blade chambers, and with part-annular ducts arranged in the casing parts and located opposite the rings of the guide blades, the part-annular duct of the inlet-side casing part being connected to the inlet duct and the part-annular duct of the outlet-side casing part being connected to the outlet duct.

Such fuel pumps are often used for the conveyance of fuel out of a fuel tank to an internal combustion engine in present-day motor vehicles and are known from practice. The casing parts of the known pump stages are manufactured mostly from metal or sintered ceramic, in order to achieve an intended stability. For example, as a result of holding forces of the jacket or owing to temperature fluctuations, forces are introduced into the pump stage, which lead to a flexion of the casing parts. Furthermore, a return body is supported over the entire circumference on one of the casing parts of the pump stage and is braced radially with respect to the casing part. Both axial and radial forces are therefore introduced into the casing part, thus likewise leading to a flexion of the casing part. However, a flexion of the casing parts leads to a variation in an axial gap between the casing parts and the impeller. Moreover, a pressure generated by the pump stage in the electric motor leads to a reduction in the axial gap between the casing part arranged nearest to the electric motor and the impeller.

The known fuel pump has the disadvantage that it is highly cost-intensive to produce because the casing parts of the pump stage are manufactured from metal or sintered ceramic.

The problem on which the invention is based is to design a fuel pump of the type initially mentioned, in such a way that it can be produced particularly cost-effectively and a flexion of the casing parts of the pump stage is largely avoided.

BRIEF DESCRIPTION OF THE INVENTION

This problem is solved, according to the invention, in that the casing parts have a disk element with one of the part-annular ducts, and in that they have, on the outer circumference of the disk element, connecting elements with force introduction surfaces for connection to adjoining components of the jacket or of the electric motor, and in that the connecting elements are arranged in the region of the neutral fiber in terms of the buckling of the casing parts, or in that supporting elements are provided which are designed for the reversal of forces introduced into the casing parts at the force introduction points and consequently for the generation of counterforces corresponding to the introduced forces.

By virtue of this configuration, a lever arm between the force introduction points and the radially inner region of the casing parts which is formed by the disk element is avoided. The connecting elements lead to an exactly determinable point at which the forces are introduced into the casing parts. Forces introduced from adjoining components into the casing parts therefore no longer lead to a flexion of the casing parts in their regions adjoining the impeller.

Owing to the invention, the casing parts can be manufactured from particularly cost-effective materials.

According to an advantageous development of the invention, the introduction of the forces into the neutral fiber in terms of buckling requires a particularly low structural outlay when the connecting elements have a rim arranged on the outer circumference of the disk element.

According to another advantageous development of the invention, a flexion of the inlet-side casing part by radial forces introduced into the pump stage through the jacket can be avoided in a simple way when the rim is arranged at half the height of the disk element of the inlet-side casing part having essentially a uniform thickness.

According to another advantageous development of the invention, a flexion of the outlet-side casing part as a result of axial forces of adjoining components can be avoided in a simple way when the rim is arranged vertically on the outer circumference of the disk element of the outlet-side casing part and has a collar projecting radially outward, and when the force introduction points for axially introduced forces are arranged on the collar.

According to another advantageous development of the invention, the connection of the regions of the outlet-side casing part which are located opposite the impeller to the force introduction points can transmit only very low forces when the outlet-side casing part has a groove between the rim and the radially inner region of the disk element.

According to another advantageous development of the invention, the outlet-side casing part has particularly high stability when radially inner supporting elements interrupt the groove and connect the disk element to the rim.

The rim of the outlet-side casing part can flex during the introduction of axial forces, without forces being introduced into that region of the disk element which is located opposite the impeller, when the rim is spaced apart from the radially outer boundary of the outlet-side casing part.

According to another advantageous development of the invention, a contribution is made to a further reduction in the moments of flexion introduced into the disk element when radially outer supporting elements are arranged, offset with respect to the radially inner supporting elements, on the radially outer side of the rim.

In the case of forces introduced axially into the outlet-side casing part, the rim can undergo deformation virtually independently of the disk element when the force introduction points for axially introduced forces are arranged on the radially outer supporting elements. This contributes to a further reduction in the moments of flexion introduced into the disk element.

According to another advantageous development of the invention, an introduction of radial forces into the outlet-side casing part over the entire circumference can be avoided in a simple way when individual force introduction points for radially introduced forces are arranged on the rim.

According to another advantageous development of the invention, a thermal deformation of the disk element of the outlet-side casing part due to waste heat from the electric motor can be avoided in a simple way when the outlet-side casing part has an annular recess between the part-annular duct and a mounting of the shaft.

The fuel pump according to the invention can be manufactured particularly cost-effectively when at least one of the casing parts is manufactured from plastic.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits numerous embodiments. To make its basic principle even clearer, one of these is illustrated in the drawing and is described below. In the drawing:

FIG. 1 shows a longitudinal section through a fuel pump according to the invention.

FIG. 2 shows a top view of an outlet-side casing part of the fuel pump fromFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a longitudinal section through a fuel pump with apump stage2 driven by anelectric motor1 and designed as a side channel pump. Thepump stage2 has an impeller arranged rotatably between twocasing parts3,4. Theimpeller5 is arranged fixedly in terms of rotation on ashaft6 of theelectric motor1 and has two rings, located opposite one another, ofguide blades8 delimiting blade chambers7. Part-annular ducts9,10 are arranged in each case, opposite the rings of theguide blades8, in thecasing parts3,4. The part-annular ducts9,10 form with the blade chambers7 aconveying chamber13 leading from aninlet duct11 to anoutlet duct12. Theinlet duct11 and theoutlet duct12 are arranged oncasing parts3,4 located opposite one another. Thecasing parts3,4 are spaced apart by means of aring14. Furthermore, the fuel pump has ajacket15 made from sheet metal.

Thejacket15 is flanged at its ends and prestresses the components of the fuel pump with respect to one another. The inlet-side casing part3 consists essentially of aplanar disk element16 and of arim17 arranged at half the height of its circumference. Therim17 is consequently arranged level with the neutral fiber in terms of the buckling of the inlet-side casing part3 and forms aforce introduction point18 for thejacket15. A flanging19 of thejacket15 engages behind therim17. Radial forces introduced from theflanging19 into therim17 consequently do not lead to a flexion of the inlet-side casing part3.

The outlet-side casing part4 has adisk element20 located opposite theimpeller5 and, near its outer circumference, arim21 arranged perpendicularly with respect to thedisk element20 and inFIG. 2 is illustrated in a top view from the side of theelectric motor1 ofFIG. 1. Acollar22 running around radially outside therim21 is led as far as thejacket15. Areturn ring23 of theelectric motor1 is supported axially on radially outer supportingelements24 of thepump stage2 which are arranged on thecollar22.Force introduction points25 for forces introduced axially into the outlet-side casing part4 are consequently arranged on the radially outer supportingelements24.Force introduction points25′ for forces introduced radially into the outlet-side casing part4 are arranged on the rim near to the radially outer supportingelements24 only. The outlet-side casing part4 has, as seen radially on the inside from therim21, agroove26 which is interrupted by radially inner supportingelements27 connecting therim21 to thedisk element20. The radially inner supportingelements27 are arranged so as to be offset with respect to the radially outer supportingelements24. Axial forces from thereturn ring23 of theelectric motor1 are introduced into the outlet-side casing part4 via the radially outer supportingelements24 and may lead to a deformation of therim21. A transmission of the forces to thedisk element20 is avoided by the arrangement of the radially inner and outer supportingelements24,27 and thegroove26 in relation to one another. When thereturn ring23 of theelectric motor1 exerts a radial prestress on the outlet-side casing part, the forces can be introduced only at theforce introduction points25′ for the radial forces. Owing to the offset of the radially inner supportingelements27 having theforce introduction points25′ for the radial forces, a countermoment is generated at thedisk element20 and prevents the flexion of the latter.

The outlet-side casing part3 has anannular recess28 in its radially inner region, as seen from the part-annular duct10. This annular recess28 decouples that region of the outlet-side casing part4 which is located opposite theshaft6 of theelectric motor1 from the region having the part-annular duct10. Moreover, the outlet-side casing part4 has amounting29 for theshaft6 of theelectric motor1.

In an alternative embodiment, not illustrated, thereturn ring23 of theelectric motor1 may also have individual supporting elements, by means of which it is supported between the radially inner supportingelements27 of the outlet-side casing part4. In this case, the force introduction points would be arranged directly on thecollar22 running around.

Claims (12)

The invention claimed is:

1. A fuel pump having a pump stage driven by an electric motor, comprising:

a jacket surrounding the electric motor and the pump stage;

an impeller arranged rotatably between two casing parts of the pump stage, an inlet duct being arranged in an inlet-side casing part of the casing parts and an outlet duct being arranged in an outlet-side casing part of the casing parts, rings of guide blades being arranged in the impeller and delimiting blade chambers, and part-annular ducts being arranged in the two casing parts and located opposite the rings of the guide blades, a part-annular duct of the inlet-side casing part being connected to the inlet duct and a part-annular duct of the outlet-side casing part being connected to the outlet duct;

wherein each of the two casing parts includes a disk element and one of the part-annular ducts and includes, on an outer circumference of the disk element, connecting elements having force introduction surfaces for connection to one of adjoining components of the jacket and the electric motor; and

wherein the connecting elements are arranged in a region of the two casing parts at which buckling of the two casing parts occurs, and supporting elements are provided which are configured to reverse forces introduced into the outlet-side casing part at the force introduction surfaces and generate counterforces corresponding to the forces introduced into the outlet-side casing part.

2. The fuel pump as claimed inclaim 1, wherein the connecting elements comprise a rim arranged on the outer circumference of each disk element.

3. The fuel pump as claimed inclaim 2, wherein on the inlet-side casing part the rim is arranged at a height of half the disk element, the inlet-side casing part having an essentially uniform thickness.

4. The fuel pump as defined inclaim 2, wherein on the outlet-side casing part the rim is arranged vertically on the outer circumference of the disk element and includes a collar projecting radially outward, and wherein force introduction surfaces for axially introduced forces are arranged on the collar.

5. The fuel pump as defined inclaim 4, wherein the outlet-side casing part includes a groove between the rim and a radially inner region of the disk element.

6. The fuel pump as defined inclaim 5, further comprising:

radially inner supporting elements which interrupt the groove and connect the disk element to the rim.

7. The fuel pump as defined inclaim 4, wherein the rim is spaced apart from a radially outer boundary of the outlet-side casing part.

8. The fuel pump as defined inclaim 6, further comprising:

radially outer supporting elements arranged, offset with respect to the radially inner supporting elements, on a radially outer side of the rim.

9. The fuel pump as defined inclaim 8, wherein the force introduction points for the axially introduced forces are arranged on the radially outer supporting elements.

10. The fuel pump as defined inclaim 4, wherein individual force introduction points for radially introduced forces are arranged on the rim.

11. The fuel pump as defined inclaim 1, wherein the outlet-side casing part includes an annular recess between one of the part-annular ducts and a mounting point of the shaft.

12. The fuel pump as defined inclaim 1, wherein at least one of the two casing parts is manufactured from plastic.

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